"Soap, since its appearance in history, has helped safeguard two of our greatest treasures: our health and our children. Health is directly related to cleanliness. Data proves that the higher the consumption of soap in a country, the lower will be the infant mortality rate.
"In industrialized countries, soap is the most-taken-for-granted and readily available personal care product used on our body daily. Soap is also the most inexpensive product we use in relation to its per use cost. In many less fortunate countries both laundry and toilet soaps are still scarce, expensive essentials . . . .
"Soap is most probably the oldest of toiletries, and, in spite of being readily available in most parts of the world, it is still scarce in many countries. The oldest literary reference to soap relates to the washing of wool and is found in clay Sumerian tablets dating about 2500 B.C.E. Sumerian was a language spoken in the area of the Tigris and Euphrates Rivers, now Southern Iraq. The patriarch Abraham and his family came from Sumer. Another Sumerian tablet, dating 2200 B.C.E. gives the formula consisting of water, alkali and cassia oil.
"Cleanliness is essential to our well being. A clean body, clean bath, clean home, and clean environment are the norm today." (Soap Technology for the 1990's, L. Spitz et al., American Oil Chemists' Society, Champaign, Ill., pp. 1-2). This reference discusses syndet and combo bars, particularly on pp. 209-229.
Synthetic surfactant-based personal cleansing bars have attracted much interest recently because they can be selected to be milder to the skin than soap-based products. This mildness, however, comes with negatives to both the manufacturer and the consumer. The bar soap manufacturer experiences difficult processability due to the sticky nature of such products, as well as high raw material costs. The consumer experiences the negative performance properties of poor lather, messy smear, bar softness, and, consequently, high wear rates.
U.S. Pat. No. 2,988,511, Mills and Korpi, issued Jun. 13, 1961, incorporated herein by reference, discloses a milled detergent bar with at least 75% by weight of: (1) 15%-55% of anionic sulfuric reaction products which do not hydrolyze unduly, said salts being selected from sodium and potassium salts, and said anionic organic sulfuric reaction products containing at least 50% alkyl glyceryl ether sulfonates, 10%-30% of which are alkyl diglyceryl ether sulfonates, the alkyl radicals containing 10-20 carbon atoms; (2) 5%-50% soap; and (3) 20%-70% of a binder material selected from freshly precipitated calcium soaps of fatty acids having 10-18 carbon atoms, freshly precipitated magnesium soap, starch, normally solid waxy materials which will become plastic under conditions encountered in the milling of soap. Paraffin is not mentioned in Mills et al. '511.
Commonly assigned U.S. Pat. No. 4,673,525, Small et al., issued Jun. 16, 1987, discloses mild personal cleansing bars based on selected mild surfactant; moisturizer; 0%-5% polymeric skin mildness aid; and some soap. This patent goes a long way in providing a practical mild personal cleansing bar; but significant processing problems have been experienced due to the sticky nature of some of the preferred ingredients.
The use of paraffin wax in synthetic surfactant-based bars, per se, is known. However, the known bars suffer from a combination of harshness and/or lather deficiencies. E.g., U.S. Pat. No. 2,653,913, van Dijck et al., issued Sep. 29, 1953, discloses bars comprising 80% synthetic anionic surfactant (selected from sodium secondary or primary alkyl sulfates or sodium dodecylbenzene sulfonate), 18% paraffin, melting point (M.P.) 140.degree.-150.degree. F., and 2% sodium alginate. The surfactants employed are non-mild surfactants.
U.S. Pat. No. 2,734,870, Lewis, issued Feb. 14, 1956, discloses bars comprising 40-60% paraffin (M.P. &gt;125.degree. F.), 2-5% fatty acid, and 60-40% sodium alkyl aryl sulfonate. The high level of paraffin in these bars results in unacceptably low lather.
U.S. Pat. No. 3,129,187, Meehan, issued Apr. 14, 1964, discloses bars comprising 50-75% sodium alkylbenzene sulfonate, 5-35% stearyl alcohol, 1-25% paraffin (M.P. 125.degree.-170.degree. F.), and 2-25% stearyl MEA. The harsh surfactants employed would result in harsh products.
U.S. Pat. No. 4,151,105, O'Roark, issued Apr. 24, 1979, discloses bars comprising 20-40% synthetic anionic surfactant (composed of sodium cocoyl isethionate and/or sodium lauryl sulfoacetate), 10-30% paraffin (M.P. 130.degree.-140.degree. F.), 5-15% powdered starch, 10-30% dextrin and 5% fatty acid. The low melting point of the wax employed would cause a substantial soil load on the lather potential and result in poor lather volumes. The synbars of the present invention are preferably free of dextrin and powdered starch.
U.S. Pat. No. 4,335,025, Barker et al., issued Jun. 15, 1982, discloses a process for making syndet bars containing a "waxy extender."